The long-standing significance of Ostrava as an economic and industrial centre of the Czech lands (from around 1850 to 1989) continues to thematically determine Ostrava's position in Czech, Czechoslovakian and Central European historiography. The social scientists studying the spiritual and religious history of 20th-century Ostrava are somewhat on the periphery, and unlike research into the persecution of the Roman Catholic clergy and monks during the time of the Protectorate and the post-February period, interest in researching this issue of the interwar period has been slightly more cautious. This paper focuses on a brief description of the institutional development of the traditional players in interwar religious life in Greater Ostrava – the Roman Catholic Church, the Evangelical Church of the Augsburg Confession, the Jewish religious community – and above all the new players in spiritual and religious life between the world wars: the Czechoslovak Church, the Association of Social Democratic Atheists and the spiritistic Brotherhood association, which used Ostrava as a centre of First Republic spiritual and religious life.